Industrial truck



Jan. 11, 1944. B, UUNSK. 2,339,12o

IIIIIIIIIIIIII CK Jan. 11, 1944. z B. uuNsKl 2,339,12o

INDUSTRIAL' TRUCK v Filed June 20, 1942 3' Sheets-Sheet 2 ATTO R N EY Jan. 11, 1944. B U| |N$K| 2,339,120

INDUSTRIAL TRUCK Filed June 20, 1942 3`Sheets-Sheet 3 Ig v 60 J v5 J? 56 40 ao f 20 lNvENToR ATTO R N EY Patented Jan. 11, 1944 Bronlslaus Ulinski, Chicago, Ill., assignor to The Yale a; Towne Manufacturing Company, Stamford, Conn., a corporation of Connecticut V Application June 20, 1942,' Serial No. 447,849

28 Claims.

This invention relates to an industrial truck of the type in which an elevating platform is adapted to be lifted relatively to one or more uprights upon the'operation 'of suitable elevating mechanism. More, particularly, my invention relates to an industrial t'ruck of the type in which the elevating platform is in the form of a 1 pair of spacedforks, and my invention will so be described. Those skilled in the artV will appreciate however, that certain features of my invention are applicable to a truck in which the platform is formed of means other than spaced load forks.

A feature of my invention is the mounting of the forks comprisingthe platform, so that they are readily adjusted vertically relativelyto the elev'ating carriage of the truck on which they are mounted for lifting movement. wherebythe lliting movement of the forks may be increased when deslred, to a considerable extent. Thus. this feature of my invention allows the forks to be secured normally to a lower'portion of the elevating carriage so that the forks may be dropped to the fioor on which the truck is placed. By particular manlpulatlon of means forming part of my invention, the forks may thereafter be adjusted Vso as to lie in an upper relatlon rela- 'tively to the elevating carriage whereby to contribute greater overall liftlng helght.

As a further feature of my invention, I utilize a novel form of mechanism whereby the adjustment of the forks relatively to the elevating carriage in several vertically spaced positions is readily obtained, preferably by mere manipulation of the parts by the elevating mechanism,

and with practically no manual operation. As a' still further feature of my invention, the means whereby the forks are secured relatively'tothe elevating cariage in several vertically spaced positions, are operable in all of the positionsof the elevating carriage, the elevating carriage' having a considerable range of movement so as to make such means of considerable importance.

A still further feature of my invention, and one which is particularly applicable to that form of my invention utilizina' spaced load lifting forks, resides in the means whereby/the forks may be adjusted into different laterall'y spaced positions. and may in each of the said laterally spaced positions be adjusted vertically into different vertically spaced posltlons as already outlined.

As a further feature of this part of my invention, the elevating vforks are supported by the elevating carriage through what I choose to term fork supports, and these fork supports are laterally slidable on the elevating carriage to contribute lateral adjustment of the forks,` all as will appear clearly in the specification that follows.

I have thus outlined the more important features of my invention in order that the mechanism to be hereinafter described may be more clearly understood. Those skilled in Ithe art will understand however that the basic contribution of my invention may be embodied in structure other than 'that which I shall hereinafter describe, and will appreciate that the claimsto be allowed me should be suillciently broad to prevent the appropriation of my invention by its embodlment in such other structures. l

Referring now to the drawings, Fig. 1 is a perspective view of an electric industrial truck having two pairs of uprights, and an elevating carrlage on which is supported a pair of lifting forks. In Fig. 1 the lifting forks are shown secured relatively to the elevating carriage in their highest Vertical position. Fig. 2 illustrates the truck of Fig. 1 with the elevating carriage in its llowermost position, andthe forks against the ground and under a skid platform. Fig. 3 shows the manner in which the parts of the truck of Figs. 1 and 2 are operated to place the forks in,

the highest position possible relatively to the elevating carriage, that being the position of the forks in Flg. 1.` Fig. 4 is.an enlarged view of certain parts of Fig. 2. Fig. 5 is a view looking to the left toward Fig. 4 in the direction of the arrows 5-5. Fig. 6 is a view taken along lines 6-8 of Fig. 5.' Fig. 7 is an enlarged view of certain of the parts of Fig. 4, with several of the parts shown in section. Fig. 7o is a view of certain of the parts of Flg. 7 in a somewhat different position. Fig. 8 is a section taken along lines 8-8 of Fig. 7. Fig. 9 is a perspective'view of one of the forks and a fork support.

Referring now more particularly to the drawings, reference letter T indicates an industrial truck of the type having an operator's platform 'I'1,'a pair of primary uprights III, secondary uprights II. adapted to be elevated on the primary uprights ID, and a lifting carrlage designated generally' by the reference numeral I2 adapted to be elevated on the secondary uprights I l. 'I'he general combination/ thus described is one which is old in the art andlno details of the truck construction nor the means for elevating the secondary uprights I I and the carriage 12 are shown for that reason. Reference may be made to the Schroeder Patent 2,059,150 granted October 27, 1936, for a showing of a truck in which uprights lother series is formed fork supports of vertically spaced rollers I4 extending from4 v a structural steel member I5 of the elevating carriage 12. There are of course two of these members I5, one for each of the 'secondary uprights II, and extending between the two members I5 and connecting those members, is what I may term a support plate I6.

A pair of duplicate which is best shown in Fig. 9, is adapted to be mounted on the support plate I6. For the particular purpose, each of the fork supports I1 has secured thereto an upper bearing member I8 having a groove I 9 whereby to slide on the upper bearing surface 28 of the support plate I6. A somewhat similar lower bearing member 2I is secured to each of the fork supports I1 and is formed with a surface 22 for Cooperation with an under bearing surface 23 of the support plate I6.` It is obvious that through the particular arrangement thus outlined the fork supports I1 may slide laterally on the bearing plate I6 into different spaced relation to one another. I shallA now proceed to describe the manner in whichthe fork supports are thus laterally moved relatively to the support plate I6 and to one another.

Referring now to the'left and right ends of the support plate I6, end bars 25 through a series of bolts 26, and mounted for rotation on and between the said end bars 25 is a threaded shaft 21, the said shaft being held by flanges 28 against late'ral movement relatively to the end bars 25. The threadedv shaft 21 has two series of threads denoted re-` spectively by reference numerals 29 and 38, one series being formed in one direction while the in the other direction, all as is readily apparent by a glance at Figs. 5 and 8. vCooperating with the series of threads 39, there is a rather novel shaped nut 3I formed with a lug 32 that fits within a slot 33 or other opening in the bearing member I8 of one of the I1. Similarly, the series of threads 29 has fitted thereon' a nut 34 similar to the nut 3I but oppositely threaded, and whose lug 35 fits within a slot 36 of the bearing member I8 of the` other fork support I1.

It will now be quite apparent that if the shaft 21 is rotated, as by a I1 toward one another Now that the conto move the fork supports or away from one another.

- struction of my invention whereby the forks are ports and-forks are mounted.

For 'a proper understanding of my invention it may be well to indicate at this time that the fork supports I1 are formed by the union of a pair of Vertical plates 38 with a channel member 39, this union being formed either by riveting, bolting or Welding as the case may be. In the particular form of the invention herein decribed the union is formed by using a series of rivets 48.

fork supports I1, one of Fig. 5, there are secured to tool cooperating with its' ends, the nuts 3I and 34 will be actuated laterally.

. latch mechanism.

asaaiao The plates 38 are grooved as at 42, and sliding within the grooves 42 are the flanges 43 of the Vertical beam 44 of each of the forks 45 best shown in Fig. 9. A series of slots 46 is formed in the back face of each beam 44, the upper end of "each slot being closed by a somewhat semicircular wearing lug 41 bolted into position by bolts 48 as is `best apparent from Fig. '1a. For cooperatingswith the lugs 41 and slots 46,1 utilize what I choose to term latches-49, it being understood that' the latches 49 and the lugs 41 of the slots 46 comprise what may be termed broadly. `Shownin the drawings, but

' not of such nature as to require a description, are

' my description limit stops to limit the movement of the forks relatively to their supports.

There is of course a latch 49 for each fork support and fork combination, and I shall conflne welded to the channel member 39 of the fork support I1, a pair of bearing lugs 58, bores 51 support I1. A circular rod 52 is mounted for rotation in the several bores 5I and is supported at its center in a bearing member 53 carried at the end of a Vertical strut 54 that is bolted' at its lower end at 55 to the support plate I6. The rod 52 is formed with a keyway 56, and each o!- the latches 49 is keyed to the rod 52 through the medium of a key 51 all as isbest seen in Fig. 8. Also as best shown in Fig. 6, the latch- 49 e'xtends' through a into one of the slots 46 of the vertical bearn portion 44 of thefork 45.

It will be noted that in this position of the parts, best seen from a study of Fig. '1, the latch 49 supports the weight of the fork 45, the latchV in turn resting against the surface '58a deflning the lower end of the slot 58 in the channel member 39. Moreover, it will be appreciated that with the parts sopositioned, should the fork supports I1 and the forks 45 be moved laterally, the latches 49 will m erely keyed to that shaft for a purpose to be described presently. 4

The shaft 52 is utilized for moving the l'atches 49 so as to permit upward movement of the fork supports I1 relatively to the forks 45.. Such release is obtained by rotating each latch 49 to the position of Fig. 'la from the position of Fig. '7, this rotation being limited by a limit pin 68.4 This rotation takes place also against the force of a spring GI that is secured at one end relatively to the strut 54 and bearing block 53, and at its other end to the shaft 52 through the medium of the` block 62 pinned at 63 to the said shaft. At the left hand end of the shaft 52, as best seen in Fig. 5, there is secured a lever 64 that in turn is secured to a cable 65. The cable passes into a reel casing 66 `and is adapted to be reeled into that casing by a spring in a manner which is well` known in the particular reel art and which per se forms nofpart of this invention. For my purposes I can use any form of reelnow being manufactured that I may find is ad'apted for the purpose. It will best be noted from Fig, 1 that even in the extreme elevated position of the carriage I2 therein illustrated, the cable 65 is readily operable to move the lever 64 and to rotate the shaft 52 and the latches 49 thereon against'the force of the spring 6I from the position of Fig. '1 into the position of Fig. 'la and against the limit pins 68.

to but one latch. Referring to' Figs. 6, '7, 'la and 9 -it willbe noted that there is slot 58 in the. channel member 39 and v slide relatively to the shaft 62 It will be interesting to note however, that this somewhat above the latches 49 from the position illustrated in Fig. '7. This movement of course is obtained by holding the forks 45 against lowering movement as hereinafter vindicated, at the same time that the carriage 12 and the fork supports l1 are lowered. It is obvious. of course, that the forks 45 may always be raised relatively tothe carriage IZ and the fork supports 11 -by the mere downward movement of the carriage IZ and the fork supports I1 relatively to the forks 45, such movement allowing a mere latchirg of the latches 49- against the pressure of the spring 91 as will be fully appreciated. v

Referring now to Figs. 2 and 3 I shall discuss briefly the functional operation of the parts of my invention in order that the construction which has been described in detail may be even better appreciated. With the parts in the posltion of Fig. 2, it will be noted that the carriage 12 is in' its extreme lowered position and that the forks 45 are` also lowered as far as possible and are in contact with the floor. The truck is now adapted to lift a skid platform 19 and thel load 11 sup-' ported thereon. If the lifting means now be operated so that the carriage 12 is elevated relatively to the secondary uprights li. it is obvious that the forks 45 will be-elevated until they reach thelposition illustrated in Fig. 3. In that position, the forks may be brought to rest against the upper surface 12 of a stack of material and assaiao ing carriage mounted for linear lifting and lowering movement on said truck, means for lifting and lowering said carriage, a load to be lifted and lowered with said elevating carriage, and means whereby said platform is readily secured to said elevating carriage in aplurality of vertically spaced positions for linear lifting and lowering movement with said carriage.

2. In a truck of the class described, an elevating carriage mounted for linear lifting and lowering movement on said truck, means for lifting and lowering said carriage, a load platform mounted for vertical sliding movement on said elevating carriage, and means whereby 'said platform is readily secured to said elevating carriage in any one of a plurality of vertically spaced positions for linear lifting and lowering movement with said with the skid 19 also supported on that stack of 4 material, either directly as illustrated, or indirectly on the forks. 45. f v

If in this particular position of the parts, the carriage 12 and fork supports l1' be now lowered, the latches 49 will not impede such lowering movement and will allow thefelevating cav-riage 12 to move into the position of Fig.'2 and therefore into the position of Fig. 3 relatively to stationary forks 45. The latches 49 will now be positioned in the lowermost slots of thx'` vertical beams 44 of' the forks 45 and against the lower surfaces of the lugs 41. At this point, by merely operating the elevating mechanism of the truck the forks 45 may be moved with the carriage 12 to the extreme position of Fig. 1, contributing the greatest possible elevating movement to the said forks, all as will be fully appreciated.

If now it is desired to move the forks back into their relation of Fig. 2 relatively to the fork elevating carriage.

3. In a truck of the class described, an elevating carriage mounted for sliding lifting and lowering movement on said truck, a load platform adapted to be lifted and lowered with said elevating carriage, and latch mechanism for securing said platform to said elevating carriage in a piurality' of vertically spaced positions for sliding lifting and lowering movement with said carriage.

4. In a truck of the class described,` an elevating carriage mounted for lifting movement on said truck, a, load platform mounted for vertical sliding movement on said elevnting carriage, latch mechanism for securing said platform against downward movement relatively to said elevating carriage in any one of a plurality of vertically spaced positions for lifting movement with said elevating oarriage, said latch mechanism permitting downward vertical movement of said elevating Carrlage relatively to said platform when said platform is held against downward vertical movement.

5. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for vertical sliding movement on said elevating carriage, latch mechanism for securing said platform against downward movement relatively to said elevating carriage in any one of a plurality of vertically supports I1 and the carriage 12, it 'is only necessary to bring the parts into the position of Fig. 3 with the forks resting at 12. By now Operating the elevating mechanism while moving the cable to withdraw the latches 49 into the posltion of la, it is possible to lift the carriage 12 andv the fork supports 11 relatively to the stationary forks 45, and into their normal relation to one another illustrated in Fig. 2. Naturally, this lifting movement of the carriage 12 and :ork supports I1 relatively to the forks 45 can only be accomplished after the release of the latches 49, which release requires first the proper spacing of the lugs 41 relatively to the latches 49 'as already described.

It will be of coursel appreciated that in all the vertical positions of the forks it is possible to adjust the forks laterally through/movement of the fork supports 11 all as has already been described.

`nism whereby to release I believe that the operation of my invention will now be quite apparent.

I now claim: -f' 1. In a trucls/o' the class described. an elevatspaced positions for lifting movement with said elevatlng carriage, said latch mechanism permitting downward verticalmovement of said elevating carriage relatively to said platform when said platform is held against downward vertical movement, and means for moving said latch mechanism to allow upward vertical movement of said elevating carriage relatively to said platform.

6. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for vertical sliding movement on said elevating carriage, latch mechanism for securlng said platformv relatively to said elevating carriage in any one of a plurality of vertically spaced positions on said carriage for lifting movement thereafter with said elevating carriage, and means for moving said latch mechasaid platform for sliding movement relatively to said elevating carriage into another one of said vertically spaced positions in which said latch mechanism again securessaid platform against downward movement relatively to said carriage. V

'1. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for vertical sliding movement on said elevating carriage, latchv platform adapted t carriage in any one of a plurality of `vertically 'spaced positions on said elevating carriage for` lifting movement'thereafter with said carriage,

said latch mechanism allowing downward moVe-,=

ment of said elevating carriage relatively to saidvf" ing carriage mounted for lifting movement on' said truck, a loadvplatform mounted for vertical sliding movement lon said elevating carriage, a latch for securing said platform for upward movement with said elevating carriage in a plurality of vertically spaced positions on said elevating carriage, said latch being ,retractible upon determined movement of said elevating carriage downwardly while said platform is held against downward movement, whereby to release said platform from said carriage.

9. In a truck of the class described, an operator's station, a pair of nprights, an elevating carriage mounted for Vertical lifting movement on said uprights, a load platform adapted to be lifted with said elevating carriage, latch mechanism whereby said load platform is readily secured to said elevating carriage in a plurality of Vertioally spaced positions, and means extending' to said latch mechanism from a position at said opi erator's station for effecting the movement of said latch mechanism to release said load platform relatively to said elevating carriage for adjustment from one of said spaced positions to another of said spaced positions, said means then allowins movement of said latch mechanism into position to sec'ure said load platform relatively to said elevating carriage in said other spaced position.

10. In a truck of the class described, an operator's station, a pair of uprights, an elevating carriage mounted for'Verti-oal lifting movement said operator's station and operable to move said latch mechanism.

.13. In a truck of the class described, an elevating carriage mounted :for lifting movement on said truck, a load platform mounted forvertical sliding movement relatively to said elevating carriage, a latch extending from said elevating carriage into underlying relation to any one of a series of vertically spaced abutments on said platform so as to lift said platform with said carriage when said platform is in any one of a series of vertically spaced positions relatively to said elevating carriage as determined by the spacing of said abntments.

14. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for Vertical on said uprights, a load platform adapted to be lifted with said elevating carriage, latch mechanism between said load platform and elevating carriage comprising a latch movable on one of said parts cooperable with any onf-y of a series of surfaces on the other part whereby said load platform is readily secured to said elevating 'carriage in a plurality of vertically spaced positions,

and means extending to said latch mechanism from a position at said operator's station for actuating said latch mechanism in all positions of said elevating carriage. .v V

11. In a tru-ck of the class described, an operator's station, a pair of uprights, an elevating carriage mounted for Vertical lifting movement on said uprights, a load platform adapted to be lifted with said elevating carriage, latch mechanism for securing said platform 'to said-elevating carriage in a plurality of vertically spaced positions, a reel mounted adjacent said operator's station, and flexible means extending from said latch mechanism to said reel and opei'able to movesaidlatchmechanism. s

12. In a truck of the class described, an operator's station, a pair of uprights, an elevating carriage mounted for Vertical lifting moyement on said uprights, a load platform mounted for Vertical sliding movement on said elevating carsliding movementon said elevating carriage, a latch extending from said elevating carriage into underlying relation to any one of a series of vertically spaced abutments on said platform so as to lift said platform with said carriage when said platform is in any one of a series of vertically spaced positions relatively to said elevating carriage as determined by the spacing of said abutments, said elevating carriage being movable vertically downwardlyrelatively to said load platform when said platform is held against following the lowering movement' of said elevating carriage. I

15. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for Vertical sliding movement on said elevating carriage, a latch extending from said elevating carriage into underlying relation to any one of a series of vertically spaced abutments on said platform so as to lift said platform with said elevating carriage when said platform is in any one of a series of vertically spaced positions relatively to said elevating carriage as determined by the spacing of said abutments, said elevating'carriage being movable vertically downwardly relatively to said load platform when said platform is held against following the elevating carriage, and means for effecting movement of said latch out of the path of said abutment to permit upward Vertical adjustment of said elevating carriage relatively to said platform.

16. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for Vertical sliding movement on'said elevating carriage, a latch extending from said elevating carriage into underlying relation to any one of a series of vertically spaced abutments on said platform so as to lift said platform with said elevating carriage when said platform is in any one of a series of vertically spaced positions relatively to said elevating carriage as determined by the spacing of said abutments, said elevating carriage being movable vertically downwardly relatively to said load platform when said platform is held against following the elevating carriage, and manual means for moving said latch out of the path` of said abutments to permit upward Vertical adjystment of said elevating carriage relatively to aid platform, said manual means requiring the pre-liminary lowering of said elevating carriage relatively to said platform.

17. In a truck of the class described, an elevating carriage mounted for lifting movement on said truck, spaoed forks adapted to be lifted with said elevating carriage, means whereby said forks -are readily secured relatively to said ele- Vating carriage in a plurality of vertically spaced positions, and means for adjusting said forks into a plurality of laterally spaced positions on said elevating carriage. 1 l

18. In a truck of the class described, an ele- Vating carriage mounted for lifting movement on said truck, fork supports mounted for lateral sliding movement on said elevating carriage, a fork mounted on each of said fork supports, and means whereby said forks are readily secured to said fork supports in a plurality of verticall spaced positions.

1 19. In a truck of the class described, an elevating carriage mounted for lifting movement on saidtruck, fork supports mounted for. lateral sliding movement on said elevating carriage, means for adjusting and securing said fork supports in laterally adjusted positions on said ele- Vating carriage, a fork mounted on each of'said fork supports, and means whereby said forks are readily secured to said fork supports in a plurality of vertically spaced positions.

20. In a truck of the class described-an elevating carriage mounted for lifting movement on said truck, fork supports mounted for lateral sliding movement on said elevating carriage, a fork mounted for Vertical sliding movement on each of said fork supports, a latch support, latch means supported on said latch support for lateral sliding movement and adapted to look said forks to said fork supports, and means whereby said latches are moved relatively to said latch support as said fork supports slide laterally on said ele- Vating carriage.

21. In a truck of the class described, an eleed transversely to said fork supports, latch means adapted for rotation with said shaft while adapted 'for sliding movement on said shaft, means l whereby said latches lock said forks to said fork supports in a plurality of vertically spaced positions, and means whereby said latches are moved 23. In a truck of the class described, an elevating carriage mounted fol` lifting and lowering movement on said truck, means for lifting and lowering said carriage, a pair of -fork supports,

means mounting said fork supports on said car-4 riage for lateral sliding motion on said carriage and for Vertical movement with said carriage, a

load fork mounted for slidiiig movement on each of said fork supports and adapted to be lifted and lowered with said fork supports when secured thereto, and means movable laterally with said fork supports for securing said forks to said fork supports in a plurality of vertically spaced positions.

24. In a `truck of the class described, an elevating carriage mounted for lifting and lowering movement on said truck, means for lifting and lowering said carriage, a pair of fork supports, means mounting said fork supports on said carriage for lateral sliding motion on said carriage and for Vertical movement with said carriage, a load fork mounted for sliding movement on each of said fork supports and adapted to be lifted and lowered with said fork supports when secured thereto, means movable laterally with said fork supports for securing said forks to said fork supports in a pluraIity of vertically spaced positions, and means for moving said laterally movable means in all lateral positions thereof to release said forks from said fork supports.

25. In a truck of the class described, an ele- Vating carriage mounted for zlifting and lowering movement on said truck,; means for lifting and lowering said carriage, a pair of fork supports, means mounting said fork supports on said carriage for lateral sliding motion on said carriage and for Vertical movement with. said carriage, a load fork mounted for sliding movement on each of said fork supports and adapted to be lifted and lowered with said fork supports when secured thereto, means moi/able laterally with said fork supports for securing said forks to said fork supports in a plurality of vertically spaced positions.

` and means extending to said laterally movable by said fork supports relatively to said shaft as said fork supports slide on said elevating carriage.

22. In avtruck of the class described, an ele- Vating carriage mounted for lifting movement on said truck, fork supports mounted for lateral sliding movement` on said elevating carriage, a fork mounted for Vertical sliding movement on each of said fork supports, a lateral shaft mounted for rotation relatively to said fork supports, latch means keyed to said shaft while adapted for sliding movement on said shaft, means whereby said lathes lock said forks to said fork supports ,in a plurality of vertically spaced positions, means whereby said latches ar'e moved with said fork supports relatively to said shaft as said fork supports slide laterally' on said elevating carriage, and means for rotating said shaft relatively to said fork supports whereby to move said latches````V to release said forks from said fork supports.

means in all Vertical positions of said fork supports for moving said laterally movable means.

26. In a truck of the class described, an elevating carriage mounted for lifting and lowering movement on said truck, means for lifting and lowering said carriage, a pair of fork supports,

' means mounting said fork supports on said carriage for lateral sliding motion' on said carrlage and for Vertical movement with said carriage, a load fork mounted for sliding movement on each of saidl fork supports and adapted to be lifted and lowered with said fork supports when secured thereto, a latch extending from each of said fork supports into underlying relation to any one of a series of vertically spaced abutments on said forks, latch support means for said latches, and means whereby said latches move laterally with said fork supports and relatively to said latch support means.`

27. In a truck of the class described, an elevating carriage mounted for lifting and lowering movement on said truck, means for lifting and of said forks keyed to said latch support member,- a series of abutments on each of said forlfs cooperable with said latches, means whereby said latohes move laterally on said supporting member as said fork supports move laterally, and means moving said latches through rotation of said latch supporting member.

28. In a truck of the elass described, an elevating carriage mounted for lifting movement on said truck, a load platform mounted for vertica1 sliding movement on said elevating` carriage, a latch extending from said elevating carriage into underlying relation to any one of a series of vertically spaced abutments on said platform so as to lift said platform with said elevating carriage when said platform is in any one of a series of vertically spaced positions relatively to said elevating carriage as determined by the spacing o! said abutments, said elevating carriage being movable vertically downwardly relatively to saidV 

